The continuing development of portable electrically powered devices such as tape recorders and playback machines, radio transmitters and receivers, and the like, creates a continuing demand for the development of reliable, long service life cells or batteries for their operation. Recently developed electrochemical cell systems that will provide a long service life utilize highly reactive anode mateials such as lithium, sodium, and the like, in conjunction with high energy density liquid cathode materials and nonaqueous electrolytes. However, the conventional cylindrical cell structures are not ideally suited for the components of these high energy cell systems. For example, in a cylindrical cell, if the anode is disposed in contact with the inner surface of the cell casing and spaced apart a fixed distance from a centrally located cathode or cathode collector by a conventional separator member, then although good contact can be provided between these components when they are assembled in the cell, the contact between these components will decrease as the anode dissolves during discharge. Consequently, the dissolving of the anode during discharge will decrease the volume of the anode and thus tend to increase the distance between anode, separator and cathode or cathode collector thereby increasing the length of the electrolyte path between these components which will result in an increase of the internal resistance in the cell.
To overcome the above disadvantage when using the components of such high energy density cell systems, it has been proposed that the components be assembled in rolled or coiled electrode assemblies (jelly roll construction) which would ensure good contact between the components of the cell during discharge. This type of cell construction is disclosed in U.S. Pat. No. 3,809,580. Although the jelly roll construction is suitable for liquid and solid cathode cell systems, jelly roll cells are rather expensive to make and time consuming to fabricate and assemble.
U.S. Pat. No. 3,796,606 discloses a cylindrical electrochemical cell whose positive electrode is in contact with the outer casing of the cell and separated by a porous separator from a negative electrode constituted by a sheet of metal having a very negative standard oxidation potential surrounding an elastically deformable current collector having a split cylindrical shape. The elasticity of the current collector enables it to maintain biased contact with the negative electrode at all times notwithstanding alteration in electrode volumes during discharge of the cell and thus to maintain the reacting surfaces of the solid positive and negative electrodes at optimum distances by continuously biasing the negative electrode against the porous separator.
It is an object of this invention to provide a cylindrical type cell employing an active metal anode in conjunction with an inner disposed cathode or cathode collector in the form of at least two arcuate bodies.
It is another object of the present invention to provide an electrochemical cell employing a liquid or solid active cathode material in conjunction with an active metal anode and a carbonaceous cathode collector in the form of at least two arcuate bodies.
It is another object of the present invention to provide a nonaqueous cylindrical cell employing a carbonaceous cathode collector in the form of at least two arcuate bodies having resilient biasing means disposed axially within the space defined by said bodies so as to force the bodies radially outward thereby maintaining the anode, separator and current collector of the cell in physical and ionic contact.
It is another object of the present invention to provide a cylindrical type cell employing an active metal anode in conjunction with an inner disposed cathode or cathode collector in the form of at least two arcuate bodies having resilient biasing means embedded with said arcuate bodies so that when said arcuate bodies are orientated to form a cylindrical type structure and then disposed axially within the cylindrical cell, the biasing means will exert a radially outward force so as to maintain the anode, separator and cathode of the cell in continuous physical and ionic contact.
It is another object of the present invention to provide a nonaqueous cylindrical cell having component parts easy to assemble and which will exhibit a relatively low internal cell resistance during discharge.
The foregoing and additional objects will become more fully apparent from the following description and the accompanying drawings.